"Well, when we can't find out who put that bar in place I might as well admit it was a ghost," spoke Tom. "Certainly, if it was done by a man, he didn't jump overboard after doing it, and he isn't here now. It sure is queer!"
Ned agreed with the last statement, at any rate.
In due time the Mars, having fought her way above the storm, came over Shopton, and then, the wind having somewhat died out, she fought her way down, and, after no little trouble, was housed in the hangar.
Tom cautioned his friends and workmen to say nothing to his father about the mysterious happening on board.
"I'll just tell him we had a slight accident, and let it go at that," Tom decided. "No use in causing him worry."
"But what are you going to do about it?" asked Ned.
"I'm going to keep careful watch over the aerial warship, at any rate," declared Tom. "If there's a hidden enemy aboard, I'll starve him out."
Accordingly, a guard, under the direction of Koku, was posted about the big shed, but nothing came of it. No stranger was observed to sneak out of the ship, after it had been deserted by the crew. The mystery seemed deeper than ever.
It took nearly a week to repair the big motor, and, during this time, Tom put some improvements on the airship, and added the finishing touches.
He was getting it ready for the final government test, for the authorities in Washington had sent word that they would have Captain Warner, in addition to Lieutenant Marbury, make the final inspection and write a report.